Content Area(s): Physical, Earth/Space Topic: Pennies dropped from a building cannot kill Short description: A recent scientific study has shown that a penny is too small and flat and cushioned by too much air to cause much of a threat, even from the height of a tall skyscraper. Instead of acting like a bullet, the penny would flutter to the ground like a leaf.
Claim: A penny falling from a skyscraper should not be a threat to people on the ground.
Keywords: air resistance, acceleration, constant speed, terminal velocity, falling objects Difficulty of Concept: Easy
MS-PS3 Energy
MS-PS3-1. Construct and interpret graphical displays of data to describe the relationships of kinetic energy to the mass of an object and to the speed of an object.
MS-ETS1 Engineering Design
MS-ETS1-1. Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.
Common Core State Standards Connections:
ELA/Literacy
RST.6-8.1 Cite specific textual evidence to support analysis of science and technical texts, attending to the precise details of explanations descriptions.
RST.6-8.8 Distinguish among facts and reasoned judgment based on research findings, and speculation in a text.
WHST.6-8.1 Write arguments focused on discipline-specific content.
WHST.6-8.9 Draw evidence from literary or informational text to support analysis, reflection and research.
SL.8.1 Engage effectively in a range of collaborative discussions(one-on-one, in groups, teacher-led) with diverse partners on grade 6 topics, texts, and issues, building on others’ ideas and expressing their own clearly.
A popular urban legend contends that if a tourist were to toss a penny from the top of a tall skyscraper, the penny could become a bullet that could severally injure or kill an unsuspecting pedestrian on the sidewalk below. It now appears that city dwellers can stop worrying about falling pennies. A recent scientific study has shown that a penny is too small and flat and cushioned by too much air to cause much of a threat, even from the height of a tall skyscraper. Instead of becoming a bullet, scientists believe the penny would flutter to the ground like a leaf.
Louis Bloomfield, a physicist at the University of Virginia, recently used wind tunnels and helium balloons to replicate the fall of pennies from skyscrapers. He said when the experimental pennies hit him in the forehead, they didn’t hurt, instead it felt like someone flicked him in the forehead but not very hard. It turns out that a falling penny does not continue to accelerate all the way to the ground. The penny will accelerate for the first 50 feet or so then the “drag force” or air resistance will slow the pennies acceleration and it will reach a terminal velocity where the downward force of gravity will be balanced by the upward force of the air. At this point, the penny will fall to the ground at a constant speed of only about 25 mph according to Bloomfield. Other studies have shown the terminal velocity of pennies can reach as high as 50 mph (80 kph) if they are falling straight down. This is still not fast enough to break the skin.
Pennies are light and flat so they experience a lot of air resistance. In a vacuum, where there is no air resistance, a penny falling from a skyscraper would continue to accelerate and might reach a speed of 200 mph by the time it reached the ground. At that speed a penny might do damage to your skull but wouldn’t drill through. "A penny is pretty much a little nothing," Bloomfield said. "It's not a very compact object.” An article in Scientific American, however, notes that other falling objects may be cause for concern. A ballpoint pen, if oriented just right, could shoot down like an arrow and could hit the ground hard enough to chip the sidewalk. So, it appears that even though some falling objects might cause harm, we have nothing to fear from common "cents."
Title: Pennies From Heaven
Content Area(s): Physical, Earth/SpaceTopic: Pennies dropped from a building cannot kill
Short description: A recent scientific study has shown that a penny is too small and flat and cushioned by too much air to cause much of a threat, even from the height of a tall skyscraper. Instead of acting like a bullet, the penny would flutter to the ground like a leaf.
Claim: A penny falling from a skyscraper should not be a threat to people on the ground.
Keywords: air resistance, acceleration, constant speed, terminal velocity, falling objects
Difficulty of Concept: Easy
Reading Level (Pit Stop 8 Article):
Flesch Reading Ease: 61.2Flesch-Kincaid Grade Level: 10.1
Lexile: 1310
Next Generation Science Standards:
MS-PS3 EnergyMS-PS3-1. Construct and interpret graphical displays of data to describe the relationships of kinetic energy to the mass of an object and to the speed of an object.
MS-ETS1 Engineering Design
MS-ETS1-1. Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.
Common Core State Standards Connections:
ELA/LiteracyRST.6-8.1 Cite specific textual evidence to support analysis of science and technical texts, attending to the precise details of explanations descriptions.
RST.6-8.8 Distinguish among facts and reasoned judgment based on research findings, and speculation in a text.
WHST.6-8.1 Write arguments focused on discipline-specific content.
WHST.6-8.9 Draw evidence from literary or informational text to support analysis, reflection and research.
SL.8.1 Engage effectively in a range of collaborative discussions(one-on-one, in groups, teacher-led) with diverse partners on grade 6 topics, texts, and issues, building on others’ ideas and expressing their own clearly.
Vocabulary Words: urban legend, drag force
Topic of Game Introduction Video: Believability of Claims
Link to Game Introduction Video: http://www.youtube.com/watch?v=Cp495DX6y9M
Full Text of Article:
A popular urban legend contends that if a tourist were to toss a penny from the top of a tall skyscraper, the penny could become a bullet that could severally injure or kill an unsuspecting pedestrian on the sidewalk below. It now appears that city dwellers can stop worrying about falling pennies. A recent scientific study has shown that a penny is too small and flat and cushioned by too much air to cause much of a threat, even from the height of a tall skyscraper. Instead of becoming a bullet, scientists believe the penny would flutter to the ground like a leaf.Louis Bloomfield, a physicist at the University of Virginia, recently used wind tunnels and helium balloons to replicate the fall of pennies from skyscrapers. He said when the experimental pennies hit him in the forehead, they didn’t hurt, instead it felt like someone flicked him in the forehead but not very hard. It turns out that a falling penny does not continue to accelerate all the way to the ground. The penny will accelerate for the first 50 feet or so then the “drag force” or air resistance will slow the pennies acceleration and it will reach a terminal velocity where the downward force of gravity will be balanced by the upward force of the air. At this point, the penny will fall to the ground at a constant speed of only about 25 mph according to Bloomfield. Other studies have shown the terminal velocity of pennies can reach as high as 50 mph (80 kph) if they are falling straight down. This is still not fast enough to break the skin.
Pennies are light and flat so they experience a lot of air resistance. In a vacuum, where there is no air resistance, a penny falling from a skyscraper would continue to accelerate and might reach a speed of 200 mph by the time it reached the ground. At that speed a penny might do damage to your skull but wouldn’t drill through. "A penny is pretty much a little nothing," Bloomfield said. "It's not a very compact object.” An article in Scientific American, however, notes that other falling objects may be cause for concern. A ballpoint pen, if oriented just right, could shoot down like an arrow and could hit the ground hard enough to chip the sidewalk. So, it appears that even though some falling objects might cause harm, we have nothing to fear from common "cents."
References/Sources:
Additional Content:
Author: Cindy Wilbur